i have a whitfield profile 20 freestanding unit I bought used. I removed the fire brick and the plate that covers the bottom portion of the air tubes also took off the exhaust fan and vacuumed all out. Cleaned photo eye and the slot it looks through (this is a gen 2 i believe).I also replaced door gasket and ignitor and had control board rebuilt. The stove works fine on low for about 10-12 hours then the burn pot overflows and the door glass goes black. I notice that adjusting the damper doesn't affect flame at all whats going on??? My flue is clear and travels vertical through my roof.